Structural adhesive formulations

ABSTRACT

Novel structural adhesive systems for metal-bonding applications. The adhesives, comprising a solution or dispersion of a polymeric material in a monomer copolymerizable therewith having incorporated therein certain phosphorus-containing compounds, are characterized by an unexpected ability of providing strong adhesion to untreated metal surfaces without adversely affecting adhesive performance, including resistance to deleterious environments. The environmental resistance of the herein described adhesives can be further improved by the addition of one or more polybasic lead salts, metal molybdates and metal phosphates.

This application is a continuation-in-part of application Ser. No.899,621, filed Apr. 24, 1978, now U.S. Pat. No. 4,223,115.

The present invention relates to adhesive compositions. Moreparticularly, the invention relates to structural adhesive compositionshaving improved adhesion to metal substrates, especially untreated metalsubstrates.

A feature of structural adhesives is their contribution to theloadbearing or stress-relieving properties of the structure in whichthey are used. The physical and chemical requirements of structuraladhesives are very exacting since the bonds must not only resist anyapplied stress but they must also not adversely affect the physicalproperties of the materials being bonded. Generally, it is desirablethat the strength of the bond be no less than that of the weakermaterial being bonded. A familiar example of an extensible applicationof structural adhesives is in plywood fabrication.

A burgeoning attractive application for structural adhesives is in thebonding of lightweight metal and thermoplastic substrates, such as inthe transportation industry, for example in fabricating vehicle bodies.As thinner steel and more aluminum are used in order to effect weightsaving, it becomes increasingly more desirable to distribute loadstresses over larger areas rather than to concentrate such stresses byriveting or spot welding. Adhesive bonding may be the only viablevehicle to achieve this end, especially when one of the members is anonmetal such as a glass fiber reinforced plastic. Adhesive bonding canreduce or eliminate costly finishing operations necessitated by rivetingand welding and present a more pleasing exterior. There are fewer holesor stress points for corrosion in bonded assemblies and dissimilarmetals can be joined with less chance of establishing galvanic corrosioncells.

The commercial structural adhesives employed with wood productsgenerally provide satisfactory results; however, structural adhesivesemployed with metal and plastic materials are not without theirdeficiencies. For example, adhesive systems which have been proposed formetal bonding have often been inconsistent in both application andbonding quality. Another such problem area is the lack in one or more ofthe essential requirements for metal to metal bonds, such as high bond,peel and impact strength and resistance to solvents, chemicals and otheraggressive environments. Many of the present structural adhesive systemsare heat-activated, that is, they require a heat energy input toinitiate the curing mechanism. The need for heat activation is ofincreasing concern in energy-short areas. The elevated activationtemperatures can also adversely affect both plastic and metal structuralcomponents. Further, many structural adhesives, while being effectivebonding agents for plastic materials, are ineffective with metalsurfaces. Still another problem, especially with metals, is thecondition of the surface(s) being bonded. For example, mill-run metalsgenerally have on their surfaces oleaginous materials resulting fromlubricants employed during forming operations or deliberately applied asa protective coating during handling, shipping and storage or as alubricant for subsequent forming operations. Most adhesive systemsrequire extensive metal preparation to remove such oleaginous films andotherwise prepare the surface for bonding. As an example, arepresentative metal pretreatment to prepare aluminum surfaces forbonding includes the following steps:

(a) The substrate is cleaned with a solvent such as acetone orperchloroethylene;

(b) The substrate is then vapor-degreased by exposure for 30 seconds totrichloroethylene vapors;

(c) The substrate is next soaked for 10-15 minutes in an alkalinecleaning solution at 70° C.;

(d) The substrate is then rinsed with tap water;

(e) After the tap water rinse, the substrate is acid etched by immersionfor 10-15 minutes in a solution maintained at 70° C. of 30 partsdeionized water, 10 parts concentrated sulfuric acid and 1 part sodiumdichromate;

(f) The acid-etched substrate is then sequentially rinsed with tap waterand deionized water; and, finally,

(g) The substrate is dried for 30 minutes at 75° C. Other extensivepretreatments are required for steel.

The acrylated adhesive systems disclosed in Briggs et al U.S. Pat. No.3,890,407 have been found to be effective for bonding oily metalsurfaces at room temperature without an extensive pretreatment. However,the Briggs et al adhesives employ an oily primer which has a shortworking or pot life, which makes application of the adhesive resindifficult. In addition, Briggs et al compositions, as do many of theacrylated adhesive systems, contain halogenated polymers which tend toevolve hydrogen chloride when exposed to high temperature baking cyclessuch as are required for curing paints, which leads to a significantincidence of underbond corrosion. Further, the overall performance ofthe Briggs et al acrylated adhesive systems in bonding aluminum alloyswhich are subsequently exposed to aggresive environments such assalinity and humidity is poor. There remains a definite need forstructural adhesive systems which are not heat activated, which areeffective in bonding both plastics and metals, which can bond metalsincluding oily metals, without extensive surface pretreatment, and whichare less susceptible to degradation when exposed to elevatedtemperatures and more resistant to aggressive environments, includingsaline and humid environments.

Following an extensive research effort, it has been discovered that theaddition of certain phosphorus-containing compositions toaddition-polymerizable materials selected from the group consisting ofethylenically unsaturated monomers, polymers derived from such monomers,and mixtures thereof, provides a series of room temperature-curablestructural adhesive systems having unexpected enhanced adhesion tosubstrates, especially metal substrates, in particular oily metalsubstrates, without requiring abrading, sand blasting, phosphatizing,etching or other extensive pretreatment of the mating surfaces, withoutadversely affecting resistance to attack by aggressive environments,including saline and humid environments. The adhesive systems of theinvention have wide application, including use as a bonding material formetal-plastic and plastic-plastic structures, as well as metal-metalstructures. The invention further provides a novel adhesive primer foractivating metal surfaces and methods for adhesive bonding employing thenovel adhesive and adhesive primer systems of the invention, as well asadhesively-bonded composite structures prepared in accordance with thepresent invention.

The novel structural adhesives of the present invention can be describedas room temperature-curable adhesives comprising at least oneaddition-polymerizable material selected from the group consisting ofethylenically unsaturated monomers, polymers derived from such monomersand mixtures thereof, which are cured through the mechanism of redoxcouple catalyst systems. In particular, the adhesive systems comprise,in combination, (1), at least one addition-polymerizable materialselected from the group consisting of ethylenically unsaturatedmonomers, polymers derived from such monomers, and mixtures thereof;(2), phosphorus-containing compound; and (3), room temperature-activeredox couple catalyst system. More specifically, the structural adhesivesystems of this invention in a first embodiment comprise, incombination, (a), at least one addition-polymerizable material selectedfrom such ethylenically unsaturated monomers, polymers derived from suchmonomers and mixtures thereof; (b), phosphorus-containing compound; (c),reducing agent; and (d), a bonding accelerator containing (e), anoxidizing agent, said oxidizing agent being reactive at room temperaturewith said reducing agent to produce free radicals effective to initiatepolymerization of said ethylenically unsaturated monomer or polymericderivative thereof. In a second embodiment, the invention adhesivesystems comprise in combination, (i), at least one polymerizableethylenically unsaturated monomer, polymer derived from such monomer,and mixtures thereof; (ii), reducing agent; and (iii), a bondingaccelerator containing a mixture of (iv), a phosphorus-containingcompound and (v), an oxidizing agent, said oxidizing agent beingreactive at room temperature with said reducing agent to produce freeradicals effective to initiate polymerization of said ethylenicallyunsaturated monomer or polymeric derivative thereof.

The novel adhesive primers of the invention comprise, in combination, amixture of a phosphorus-containing compound and an oxidizing agent, saidoxidizing agent being reactive at room temperature with a reducing agentto produce free radicals effective to initiate polymerization ofaddition-polymerizable ethylenically unsaturated monomers and polymersderived from such monomers.

The invention includes, in one aspect, a multi-part adhesive systemcomprising (I), as a polymerizable adhesive base composition, a mixturecontaining at least one polymerizable material selected from the groupconsisting of ethylenically unsaturated monomer, polymer derived fromsuch monomer, and mixtures thereof; a phosphorus-containing compound;and a reducing agent; and (II), a bonding accelerator containing anoxidizing agent, the oxidizing agent being reactive at room temperaturewith said reducing agent to produce free radicals effective to initiatepolymerization of addition-polymerizable monomers and polymers,including mixtures thereof.

In another aspect, the invention provides multi-part adhesive systemscomprising (I), as a polymerizable adhesive base composition, a mixtureof at least one polymerizable material selected from the groupconsisting of ethylenically unsaturated monomer, polymer derived fromsuch monomer, and mixtures thereof and a reducing agent; and (II), as abonding accelerator, a mixture of a phosphorus-containing compound andan oxidizing agent, the oxidizing agent being reactive at roomtemperature with said reducing agent to produce free radicals effectiveto initiate polymerization of ethylenically unsaturated monomers andpolymers, including mixtures thereof.

Yet another aspect of the invention provides a process for bondingsurfaces, especially metal surfaces, which comprises, (A), applying toat least one of such surfaces a bonding accelerator containing anoxidizing agent as defined herein; (B), applying to at least one of suchsurfaces a base adhesive composition comprising a mixture containing anaddition-polymerizable monomer or polymer, a phosphorus-containingcompound and a reducing agent; and (C), placing the surfaces so treatedin abutting relationship until the adhesive composition polymerizes toeffect bonding of the surfaces to provide a unitary bonded compositestructure.

A further aspect of the invention provides a process for bondingsurfaces, especially metal surfaces, particularly oily metal surfaces,which comprises, (A), applying to at least one of such surfaces abonding accelerator containing a mixture of a phosphorus-containingcompound and an oxidizing agent as defined herein; (B), applying to atleast one of such surfaces a base adhesive composition containing atleast one addition-polymerizable monomer or polymer and a reducingagent; and (C), placing the thus-treated surfaces in abuttingrelationship until the adhesive composition polymerizes to effectbonding of the surfaces to produce a unitary bonded composite structure.

A yet further aspect of the invention provides a process for bondingsurfaces, including metal surfaces, and including oily metal surfaces,which comprises, (A), applying to at least one of such surfaces anadhesive mass containing at least one addition-polymerizable monomer orpolymer, reducing agent, phosphorus-containing compound and oxidizingagent, as defined herein and, (B), placing the thus-treated surfaces inabutting relationship until the adhesive composition polymerizes toeffect bonding of the surfaces to produce a unitary bonded compositestructure.

The adhesive systems of this invention have been found to increaseunexpectedly the bonding of untreated surfaces, including oily metals,especially steel, aluminum and copper, without deleteriously affectingthe resistance of the bonded assemblies to attack from aggressiveenvironments. In addition, the concepts of the invention now permit theuse as metal bonding agents of many structural adhesive systems whichheretofore were effective only for bonding plastic materials. Further,the herein-described adhesive systems are aerobic, that is, thecompositions remain stable in storage indefinitely in the absence of air(oxygen) and will cure at room temperature in the presence of air oroxygen to form tough durable bonds. They can thus be employed with bothporous and solid substrates, unlike the anaerobic adhesives whichrequire the presence of oxygen for storage and cannot be used on poroussubstrates containing air in their pores because such adhesives requirethe absence of air for curing.

As noted, the present invention provides a series of novel structuraladhesives containing as essential component at least oneaddition-polymerizable ethylenically unsaturated monomer or a polymerderived from such monomer, a phosphorus-containing compound and a roomtemperature-active redox couple catalyst system.

A first class of room temperature-curable structural adhesive systemcomprises

I. As a polymerizable adhesive composition, a mixture of

1. a polymer-in-monomer syrup consisting essentially of

(i) from about 2 to about 60, preferably about 5 to about 60, weightpercent of at least one addition polymer;

(ii) From about 10 to about 98, preferably about 15 to about 80, weightpercent of at least one polymerizable monomeric liquid olefinicallyunsaturated compound having at least one >C═C< group, said >C═C< grouppreferably having the structure CH₂ ═C>, said group being preferentiallyterminally located; and

(iii) from zero to about 30, preferably about 0.5 to about 15, weightpercent of a polymer containing the group ----CH₂ CCl═CH--CH₂)_(n),wherein n is an integer;

wherein (i) and (ii) are present as a partial polymerization product of(ii) or of (ii) in the presence of (iii); the mixture of (i) and (ii) or(i), (ii) and (iii) being a syrup of polymeric materials disdolved ordispersed in monomer in which syrup the amount of (i) derived from (ii)is in the range from about 2 to about 90, preferably about 2 to about60, weight percent, based on total weight of (i), (ii) and (iii);

2. from zero to about 5 percent by weight of polymerizable adhesivecomposition of at least one unsaturated dicarboxylic acid ester;

3. from zero to about 10 percent by weight of polymerizable adhesivecomposition of at least one unsaturated polyester resin;

4. from zero to about 20 percent by weight of polymerizable adhesivecomposition of at least one unsaturated carboxylic acid;

5. from zero to about 40 percent by weight of polymerizable adhesivecomposition of at least one monomeric acrylic or methacrylic acid ester,said ester (5) being in addition to any such ester employed in 1 (ii);

6. from zero to about 50 percent by weight of polymerizable adhesivecomposition of at least one polyvinyl alkyl ether; and

7. from zero to about 1 percent by weight of polymerizable adhesivecomposition of at least one waxy substance selected from the groupconsisting of paraffin wax, montan wax, beeswax, ceresine wax andspermaceti wax;

8. an effective amount of at least one phosphorus-containing compound;and

9. an effective amount of at least one reducing agent;

the amount of (1), in percent by weight, being 100 minus the combinedpercents by weight of (2) thru (9); and

II. As a bonding accelerator, an effective amount of at least oneoxidizing agent, said oxidizing agent being reactive at room temperaturewith said reducing agent to generate free radicals effective to initiateaddition polymerization of said polymerizable adhesive composition.

A particularly preferred embodiment of such first class of roomtemperature-curable adhesive system comprises

I. As a polymerizable adhesive composition, a mixture of

1. a first syrup of polymethylmethacrylate, polystyrene andpolychloroprene in monomeric methyl methacrylate and styrene, said firstsyrup being in the form of a partial polymerization product of methylmethacrylate and styrene in polychloroprene, the polychloroprene beingpresent in an amount from about 1 to about 25 percent by weight ofpolychloroprene, methyl methacrylate and styrene, the balance beingessentially methyl methacrylate and styrene with the methyl methacrylatepredominating;

2. methacrylic acid;

3. a second syrup of at least one polymer of at least one alkyl ester ofacrylic or methacrylic acid, the alkyl moiety of such ester containingfrom 1 to 8 carbon atoms, said syrup being in the form of a partialpolymerization product of said alkyl ester in methyl methacrylate, saidpolymer being present in an amount from about 15 to about 60 percent byweight of such second syrup;

the relative proportions of (1), (2) and (3) being from about 10 to 52percent by weight of (1), from about 7 to not more than 15 percent byweight of (2) and from about 33 to about 83 percent by weight of (3);

4. an effective amount of at least one phosphorus-containing compound;and

5. an effective amount of at least one reducing agent; and

6. as a bonding accelerator, an effective amount of at least oneoxidizing agent, said oxidizing agent being reactive at room temperaturewith said reducing agent to generate free radicals effective to initiateaddition polymerization of said adhesive composition.

With respect to the herein-disclosed classes of structural adhesivesystem, the invention includes, in each case and all preferredembodiments thereof, adhesive systems wherein the phosphorus-containingcompound is incorporated into the bonding accelerator. In suchinstances, the phosphorus-containing compound is generally omitted fromthe polymerizable adhesive compositions as described for each class.Such omission, although preferred, is not mandatory.

Polymer-in-monomer syrups, compositionally as well as their preparation,are well-known in the art. Representative syrups, including precursorliquid monomer compounds containing at least one olefinicallyunsaturated group, and their preparation are disclosed in U.S. Pat. Nos.3,333,025; 3,725,504; and 3,873,640. Briefly, such syrups areconveniently prepared by deaerating the starting mixture consistingessentially of at least one polymerizable liquid olefinicallyunsaturated compound and, when used, polymer containing the group --CH₂--CCl═CH--CH₂)_(n), for a short period at about 40° C. under vacuum andthen heating the mixture to about 75° C. under an inert gas atmosphere.A catalyst, for example, a free radical-generating catalyst such asbenzoyl peroxide or azodiisobutyric acid dinitrile, is then added,preferably in the form of a solution. The quantity of catalyst added issuch that it will be completely consumed when the desired viscosity isreached. After the reaction is completed the polymer-in-monomer syrup iscooled. Preferably, the syrups have a viscosity in the range from about500 to about 1,000 mPa.s at 20° C.

Monomeric liquid olefinically unsaturated compounds suitable for use inthe several classes of adhesives for forming polymer-in-monomer syrupsand as additional polymerizable materials are characterized by thepresence of at least one ##STR1## The olefinically unsaturated group ispreferably a vinyl group, more preferably terminally located withacrylic and substituted acrylic monomers being currently preferred.Representtive olefinically unsaturated monomers include, withoutlimitation, methyl methacrylate, butyl methacrylate, ethyl acrylate,diethylene glycol dimethacrylate, methacrylic acid, acrylic acid,acrylonitrile, methacrylonitrile, styrene, vinyl styrene, vinyl acetate,chlorostyrene, glycidyl methacrylate, itaconic acid, acrylamide,methacrylamide, vinylidene chloride, 2,3-dichloro-1,3-butadiene,2-chloro-1,3-butadiene, methylstyrene and n-butylstyrene.

Polymers containing the grouping --CH₂ --CCl═CH--CH₂)_(n), wherein n isan integer, are well-known in the art under the name neoprene, which isproduced by the polymerization of 2-chloro═1,3-butadiene. Furtherelucidation would be superfluous.

Unsaturated dicarboxylic acid esters suitable for use in the inventionare preferably alkyl esters, with the alkyl moiety having from 1 to 18,preferably 1 to 8, carbon atoms. Substantially any unsaturateddicarboxylic acid can be employed, with fumaric and maleic acids beingparticularly preferred.

Unsaturated polyester resins suitable for use in the adhesive systemsdescribed herein are well-known in the art. Such resin esters arederived from polycarboxylic acids and polyhydric alcohols, preferablydicarboxylic acids and dihydric alcohols, at least one of the acid andalcohol components being unsaturated. Preferably, the unsaturatedpolyester resin component will contain a relatively large number ofdouble bonds and be derived from short chain aliphatic polyhydricpolyols, such as ethylene glycol and 1,3-propylene glycol, and shortchain unsaturated polybasic acids, such as fumaric acid and maleic acid.Such resins can contain quantities of longer chain polyol such as1,6-hexanediol, as well as higher polybasic acids, such as adipic acidand phthalic acid.

Unsaturated carboxylic acids which can be used to advantage in thepractice of the invention include both monocarboxylic and polycarboxylicacids. At the present time, olefinically unsaturated monocarboxylicacids are preferred, with acrylic acid and methacrylic acid beingespecially preferred.

Polyvinyl alkyl ethers suitable for use in the several classes ofadhesive described herein are well-known in the art. Such ethers willpreferably contain 1-8, more preferably 1-4, carbon atoms in the alkylmoiety of said ether. Likewise, styrene-acrylonitrile polymers arewell-known for in the art as are chlorosulfonated polyethylenes andchlorinated polyethylenes. Further discussion of these materials isconsidered unnecessary.

Phosphorus-containing compounds which are suitable for use in each classof structural adhesive system, admixed into polymerizable adhesivecomposition, bonding accelerator, or both polymerizable adhesivecomposition and bonding accelerator, are selected from the groupconsisting of phosphoric acid and organic derivatives of phosphinicacid, phosphonic acid and phosphoric acid, said organic derivativeshaving at least one organic moiety characterized by the presence of atleast one functional group, preferably terminally located. Such organicderivatives can be saturated or unsaturated, and preferably have atleast one organic moiety characterized by the presence of at least oneunit of olefinic unsaturation. More particularly, suchphosphorus-containing compounds have the characteristic formulae:##STR2##

wherein each R is the same or different, and each R is independently adivalent organic radical directly bonded to the phosphorus atom througha carbon-phosphorus bond, said divalent radical being selected from thegroup consisting of divalent unsubstituted organic radical and divalentorganic radical having at least one substituent group selected from theclass consisting of halogen, hydroxyl, amino, alkyl radical containingfrom 1 to 8, preferably 1 to 4, carbon atoms and aryl radical having atleast one moiety containing at least one aromatic nucleus; and whereineach X is the same or different, and each X is independently afunctional group selected from the class consisting of hydrogen,hydroxyl, amino, mercapto, halogen and CH₂ ═C>; ##STR3##

wherein R and X are as previously defined; and R¹ is hydrogen or --R²--X, wherein R² is a divalent organic radical directly bonded to theoxygen radical through a carbon-oxygen bond, said divalent radical R²being selected from the group consisting of divalent unsubstitutedorganic radical and divalent organic radical having at least onesubstituent group selected from the class consisting of halogen,hydroxyl, amino, alkyl radical containing from 1 to 8, preferably 1 to4, carbon atoms and aryl radical having at least one moiety containingat least one aromatic nucleus and X is as previously defined; and##STR4##

wherein R¹ is as previously described.

A currently preferred group of phosphorus-containing compound has theformula ##STR5##

wherein R³ is selected from the group consisting of hydrogen, halogen,an alkyl group having from one to 8, preferably one to 4, carbon atoms,and CH₂ ═CH--; R⁴ is selected from the group consisting of hydrogen, analkyl group having one to 8, preferably one to 4, carbon atoms; A isselected from the group consisting of --R⁵ O-- and R⁶ O)_(n), wherein R⁵is an aliphatic or cycloaliphatic alkylene group group containing fromone to 9, preferably 2 to 6, carbon atoms; R⁶ is an alkylene grouphaving from one to 7, preferably 2 to 4, carbon atoms; n is an integerfrom 2 to 10, and m is one or 2, preferably one.

In the several formulai I-IV, the divalent organic radicals R and R² canhave a compound structure, that is, the radical can contain at leastone, or a series of at least two, unsubstituted or substitutedhydrocarbon group(s) containing or separated from each other by --O--,--S--, --COO--, --NH--, --NHCOO--, and --R⁷ O)_(n), wherein R⁷ is analkylene group group containing from 2 to 7, preferably 2 to 4 carbonatoms, and p is an integer from 2 to 10. Preferably, the divalentradical is an alkylene radical having a straight chain or ring of fromone to 22, preferably one to 9, carbon atoms in any nonrepeating unit.It will be understood that divalent radicals having a compound structurewould have two or more of such straight chains or rings. The divalentradicals can be saturated or unsaturated; aliphatic, cycloaliphtic oraromatic; and, with compound structures, can include mixtures thereof;and generally have from 1 to about 22 carbon atoms in each chain or ringof carbon atoms.

In the several formulae I--III, representative X--R-- and X--R² --radicals include, without limitation thereto, lower alkenyl,cyclohexenyl, hydroxylower alkenyl, halo-lower alkenyl, carboxy-loweralkenyl, lower alkyl, amino-lower alkyl, hydroxy-lower alkyl,mercapto-lower alkyl, alkoxy-lower alkyl, halo-lower alkyl,di-phosphonomethyl-amino-lower alkyl, phenyl-hydroxy-phosphonomethyl,aminophenyl-hydroxy-phosphonomethyl, halophenyl-hydroxy-phosphonomethyl,phenyl-amino-phosphonomethyl, halophenyl-amino-phosphonomethyl,hydroxy-phosphonomethyl, lower alkyl-hydroxy-phosphonomethyl, halo-loweralkyl-hydroxy-phosphonomethyl and amino-loweralkyl-hydroxyphosphonomethyl; the term "lower" referring to a groupcontaining from 1 to 8, preferably 1-4 carbon atoms.

Phosphorus-containing compounds having vinyl unsaturation are preferredover such compounds having allylic unsaturation, with monoesters ofphosphinic, phosphonic and phosphoric acids having one unit of vinyl orallylic, especially vinyl, unsaturation presently being preferred.Representative phosphorus-containing compounds include, withoutlimitation, phosphoric acid; 2-acryloyloxyethyl phosphate;bis-(2-acryloyloxyethyl) phosphate; methyl-(2-methacryloyloxyethyl)phosphate; ethyl methacryloyloxyethyl phosphate; methyl acryloyloxyethylphosphate; ethyl acryloyloxyethyl phosphate; compounds of Formula IVwherein R³ is hydrogen or methyl and R⁴ is propyl, isobutyl, ethylhexyl,halopropyl, haloisobutyl or haloethylhexyl; vinyl phosphonic acid;cyclohexene-3-phosphonic acid; alphahydroxybutene-2-phosphonic acid;1-hydroxy-1-phenylmethane-1,1-diphosphonic acid;1-hydroxy-1-methyl-1-1-diphosphonic acid; 1-amino-1-phenyl-1,1-diphosphonic acid; 3-amino-1-hydroxypropane-1, 1-diphosphonic acid;amino-tris-(methylenephosphonic acid); gamma-aminopropylphosphonic acid;gamma-glycidoxypropylphosphonic acid; phosphoric acid-mono-2-aminoethylester; alkyl phosphonic acid; allyl phosphinic acid;β-methacryloyloxyethyl phosphinic acid; diallylphosphinic acid;bis(β-methacryloyloxyethyl) phosphinic acid and allylmethacryloyloxyethyl phosphinic acid.

Regardless of whether incorporated into the polymerizable adhesivecomposition or bonding activator, the phosphorus-containing compoundwill be present in an amount in the range from about 0.1 to about 20,preferably about 2 to about 10 weight percent, based on total weight ofpolymerizable adhesive composition, including reducing agent.

The bonding activators which are employed in the adhesive systems ofthis invention consist essentially of

(1) from about 0.5 to about 30, preferably about 1 to about 10 weightpercent, based on total weight of bonding activator, of at least oneoxidizing agent which can function as an oxidant of a redox couplecatalyst system; and

(2) from about 70 to about 99.5 weight percent, based on total weight ofbonding accelerator, of carrier vehicle.

The room temperature-reactive redox couple catalyst systems which areemployed in the adhesive systems of this invention are well-known andneed not be discussed herein in detail. Basically, such systems compriseat least one oxidizing agent and at least one reducing agent which arecoreactive at room temperature to generate free radicals effective inthe present invention, to initiate addition polymerization reactions.Substantially any of the known oxidizing and reducing agents which areso coreactive can be employed in the practice of the present invention.Representative oxidizing agents include, without limitation, organicperoxides such as benzoyl peroxide and other diacyl peroxides,hydroperoxides such as cumene hydroperoxide, peresters such ast-butylperoxybenzoate; ketone hydroperoxides such as methyl ethylketone, organic salts of transition metals such as cobalt naphthenate,and compounds containing a labile chlorine such as sulfonyl chloride.Representative reducing agents include, without limitation, sulfinicacids; azo compounds such as azoisobutyric acid dinitrile;alpha-aminosulfones such as bis(tolylsulfonmethyl) amine,bis-(tolylsulfonmethyl) ethyl amine and bis-(tolylsulfonmethyl)-benzylamine; tertiary amines such as diisopropyl-p-toluidine, dimethyl anilineand dimethyl-p-toluidine; and amine-aldehyde condensation products, forexample, the condensation products of aliphatic aldehydes such asbutyraldehyde with primary amines such as aniline or butylamine. The useof known accelerators and promoters with the redox couple catalystsystems can be advantageous. Preferably, the oxidizing agent will bepresent in an amount in the range from about 0.5 to about 30, preferablyabout one to about 10, percent by weight of bonding accelerator, withthe amount of reducing agent being in the range from about 0.05 to about10, preferably about 0.1 to about 6, percent by weight of polymerizableadhesive composition. With the fourth class of adhesive systems, thebonding accelerator will contain at least one of the following materialsat the indicated concentrations: tertiary amine, 0.01-5, preferably0.01- 1.5, wt.-%; transition metal organic salt, 0.01-5, preferably0.01-2.5, wt.-%; and free radical generator, 0.05-10, preferably 0.05-5,wt.-%; based on total weight of accelerator.

The carrier vehicles which are suitable for use in the bondingactivators of the present invention can be a simple inert solvent ordiluent such as methylene chloride, or butyl benzyl phthalate, includingmixtures of such solvents or diluents. The carrier vehicle shouldcontain not more than 5% by weight of any moiety which is reactive withthe oxidizing agent at room temperature. The carrier vehicle can be amore complex mixture including at least one film-forming binder inaddition to inert solvent or diluent. In this case, the film-formingbinder is preferably substantially inert with respect to the oxidantwhich is present in the primer composition. A particularly preferredcarrier vehicle comprising at least one film-forming binder is anadmixture comprising about 0.05 to about 50 percent by weight of, (1),of at least one saturated organic polymeric film-forming binder having aglass transition temperature in the range from about 0° C. to about 150°C. or, (2), at least one polymer-in-monomer syrup as described herein;and from about 40 to about 99 percent by weight of at least one organicsolvent capable of maintaining the film-forming binder,phosphorous-containing compound when incorporated into the bondingactivator composition, and oxidizing agent as a stable solution ordispersion. Among the polymeric film-forming binder materials which canbe employed in the carrier vehicle are without limitation,polyalkylacrylates and methacrylates and copolymers thereof, polystyreneand copolymers thereof, vinyl polymers and copolymers, polyesters,polyketones, polysulfones, phenolic resins, polyvinyl butyrals, andpolycarbonates. The carrier vehicle can contain, in addition to solventor solvent and film-forming binder, additives such as externalplasticizers, flexibilizers, suspenders, and stabilizers, providing thatany such additives do not unacceptably adversely affect the stability ofthe activator compositions.

The novel adhesive primer compositions of the present invention, whichare especially useful for activating metal surfaces, particularlyuntreated metal surfaces, for adhesive bonding consist essentially of

(1) at least one oxidizing agent as previously described;

(2) from about 0.1 to about 20, preferably about 0.25 to about 2,percent by weight of total primer composition, of at least onephosphorus-containing compound as previously described; and

(3) a carrier vehicle as previously described. Such primer compositionsare especially adapted for use with the herein-describedaddition-polymerizable adhesive composition-reducing activator adhesivesystems.

The primer compositions are readily prepared by any of the knownstandard blending procedures. The primers can likewise be applied by anyconventional technique such as brushing, roller coating, flow coating,reverse roller coating, spraying, and electrostatic spraying. It ispreferred that the primer composition be permitted to dry prior tocontacting the primed substrate with the adhesive mass. Primed metalsurfaces can be stored for periods in excess of six months with noapparent loss of adhesive capability.

During the development of the herein described adhesive systems andprimer compositions, the addition of phosphorus-containing compound topolymerizable acrylic adhesive compositions has a retarding effect whichis directly proportional to the amount of such compound. It wasdiscovered that the addition of from about 0.01 to about 10, preferably0.5 to 5, percent by weight of polymerizable adhesive compositions ofcertain tertiary amines having the formula ##STR6##

wherein Z is methylene; Y is selected from the group consisting ofhydrogen, hydroxy, amino, halogen, alkyl of 1 to 8, preferably 1 to 4,carbon atoms, and alkoxy having from 1 to 8, preferably 1 to 4, carbonatoms; a is zero, or 1; and b is 1 or 2; is effective to accelerate thecure of such compositions containing said phosphorus compounds.Especially preferred of such tertiary amines are N,N-dimethyl anilineand N,N-dimethyl amino methyl phenol. It is significant to note thattertiary amines which do not have the formula V do not appear to beeffective as cure accelerators for polymerizable adhesive compositionscontaining phosphorus compounds having the formulae I-IV.

The use of the novel phosphorus compound-containing primer compositionswith the herein described polymerizable adhesive compositions whichthemselves contain no phosphorus compound having the formulae I-IV hasno deleterious effect on the cure rate of the adhesive systems; however,such phosphorus compound-containing bonding accelerators quite oftenevidence a loss in their bonding ability, oft times after only a fewhours. It was discovered that the working life of the primercompositions could be significantly increased to two weeks or more withno deleterious side effects by the addition of from about 0.01 to about5, preferably about 0.1 to about 1.0, weight percent, based on weight ofprimer composition, of at least one free radical scavenger, such asp-benzoquinone, hydroquinone, p-methoxyphenol, 1,4-dimethoxy-benzenechloranil, 2,6-di-t-butyl-p-cresol.

It has further been found that the environmental resistance of theherein described adhesive systems can be improved by the addition offrom about 0.005 to about 15, preferably about 0.1 to about 10, percentby weight, based on total weight of polymerizable adhesive compositionof a mixture of a metal molybdate selected from the group consisting ofzinc molybdate, calcium molybdate, barium molybdate, strontium molybdateand mixtures thereof, and a metal phosphate selected from the groupconsisting of zinc phosphate, calcium phosphate, magnesium phosphate andmixtures thereof, said metal molybdate being present on a volumeconcentration basis of from about 2 to about 3 parts per part of saidmetal phosphate. Such mixtures, including their preparation, are morefully described in U.S. Pat. No. 4,017,315, the disclosure of which isincorporated herein by reference.

It has also been discovered that polybasic lead salts of phosphorus acidand saturated and unsaturated organic dicarboxylic acids and acidanhydrides, particularly dibasic lead phthalate, monohydrous tribasiclead maleate, tetrabasic lead fumarate, dibasic lead phosphite andmixutes thereof; and zinc oxide, in an amount in the range from about0.1 to about 15, preferably about 1 to about 10, percent by weight,based on total weight of polymerizable adhesive composition, areeffective in improving environmental resistance.

Other additives conventionally employed in adhesive compositions, suchas fillers, pigments and the like can be added to the herein-describedadhesives systems.

The base adhesive compositions, bonding accelerators and adhesive primercompositions are prepared by conventional methods, such as aredisclosed, for example, in U.S. Pat. Nos. 3,832,274 and 3,890,407.

The adhesive systems and primer compositions of the present inventionmay be used to bond metal surfaces, such as steel, aluminum and copper,to a variety of substrates, including metals, plastics and otherpolymers, fibers, glass, ceramics, wood and the like. The adhesivesystems can be employed as multipack adhesive systems where one partcontains the polymerizable adhesive composition and a second partcontains the herein-described bonding accelerators. Alternatively, itcan be employed as a primer system. When used as a multipart system, oneor both surfaces to be joined are coated with the adhesive systemobtained by mixing the individual parts, and the surfaces are placed incontact with each other. In the primer system, the primer composition orbonding activator is first applied to one or both of the surfaces to bejoined, and the adhesive resin mass containing polymerizable adhesivecomposition is applied to at least one of the surfaces, which are thenplaced in contact with each other. In the general case, the primersystem is operationally more convenient.

It is a particular feature of the present invention that thehereindescribed primer and adhesive compositions can be employed to bondmetal substrates such as steel, aluminum and copper with little, if any,pretreatment of the metal surface prior to application of the primer oradhesive, as the case may be. Thus, bonding can be effected even to oilymetal surfaces which are otherwise clean without an extensivepretreatment as is usually required with the vast majority of currentlyavailable primers and adhesives. Additionally, the adhesive systems ofthis invention provide effective bonding at room temperature, thus heatis not required either for applying the adhesive systems to thesubstrates or for curing. They can also be employed on poroussubstrates, unlike the anaerobic adhesives which require the exclusionof air and thus cannot be used on surfaces containing air in theirpores.

The invention is illustrated by the following examples, wherein allparts, proportions and percentages are by weight unless otherwiseindicated.

EXAMPLE 1

A series of adhesive resins and polymer-in-monomer syrups are preparedas follows:

Adhesive Resin I: To a suitable reaction vessel equipped with stirrer,thermometer, dry air purge, and Dean Stark trap and condenser, wherecharged 1.0 mole of polycaprolactone triol, molecular weight average of540, (PCP-0300 available from Union Carbide Corporation), 0.65 mole ofpolycaprolactone diol, average molecular weight of 2,000, (PCP-0240available from Union Carbide Corporation) and sufficient methylmethacrylate monomer to give a non-volatile content of 65% after allingredients had been added. A known excess of methyl methacrylatemonomer was added and the contents of the reaction vessel heated toboiling with stirring and dry air purge. The excess methyl methacrylatemonomer was removed along with any water present in the reaction vessel,as methyl methacrylate and water for a low boiling azeotrope. Thetemperature was lowered to 60° C., and 4.3 moles of toluene diisocyanateadded to the reaction vessel. The temperature was maintained at 70°-80°C., until all --OH groups had been reacted (about 2 hours), yielding--NCO terminated urethane dissolved in the methyl methacrylate monomer,4.3 moles of hydroxy ethyl methacrylate (HEMA) were then added to thereaction vessel and the temperature held at 70°-80° C., until all --NCOhad been reacted (about 2 hours). A slight excess (about 10%) HEMA maybe added to facilitate completion. Dibutyl tin dilaurate or stannousoctoate catalyst may also be used.

Polymer-in-monomer syrup I: Following the procedure of Example I ofU.S.A. Pat. No. 3,333,025, eighteen parts, by weight, of polychloroprene(neoprene WRT) are dissolved in 76 parts of methylmethacrylate and 6parts of styrene. The mixture is heated to 80° C., after which 0.01percent of azobisisobutyronitrile is added and the material partiallypolymerized to a viscosity of about 170,000 cps.

Polymer-in-monomer syrup II: A medium molecular weight poly(methylmethacrylate) homopolymer, "Acryloid®" (TM, Rohm & Haas Company) A-11,is blended with methyl methacrylate to provide a 70 percent resin solidspolymer-in-monomer syrup. Alternatively, polymer-in-monomer syrup II canbe made as a partial polymerization product of poly(methyl methacrylate)homopolymer in monomeric methyl methacrylate by polymerizing methylmethacrylate by a process similar to that employed in preparing Syrup I.

EXAMPLE II

Adhesive systems are prepared in a conventional manner having thefollowing compositions (amounts in weight percent):

    ______________________________________                                        Adhesive System      II-1    II-2    II-3                                     ______________________________________                                        Polymerizable adhesive composition                                            Adhesive resin I (Ex. I)                                                                           17.68   15.68   17.68                                    Carboxylated Poly(1,3-butadiene/                                                                   12.47   11.24   12.47                                    acrylonitrile) elastomer "Hycar"                                              (TM, E. I. duPont) 1072                                                       Methyl methacrylate  56.21   48.74   56.21                                    Methacrylic acid     8.90    7.80    8.90                                     2-methacryloyloxyethyl phosphate                                                                   --      6.1     --                                       N,N-diisopropanol-p-toluidine                                                                      1.3     1.1     1.3                                      N,N-dimethylaniline  --      1.8     --                                       Moly® (TM,Amax) FR-21.sup.a                                                                    --      4.4     4.4                                      Bonding accelerator:                                                          Benzoyl peroxide     50.     50.     50.0                                     2-methacryloyloxyethyl phosphate                                                                   --      --      1.5                                      Dibutyl phthalate    50.     50.     --                                       Methylene chloride   --      --      66.0                                     Trichloroethane      --      --      14.4                                     Methyl isobutyl ketone                                                                             --      --      8.6                                      Syrup I              --      --      1.5                                      ______________________________________                                         .sup.a A mixture of calcium molybdate (3 vols.) and zinc phosphate (2         vols.) on inert substrate.                                               

After blending and agitating the ingredients of the polymerizableadhesive compositions and the bonding accelerators to obtain separatehomogeneous compositions, the adhesive systems are employed to bondsteel-steel and aluminum-aluminum at room temperature. In the case ofadhesive systems II-1 and II-2, the bonding accelerator is admixed withthe adhesive composition in an amount of 4 parts by weight per 100 partsby weight of polymerizable adhesive composition. The fully-mixedadhesive system is coated onto one mating surface and a second uncoatedmating surface is pressed onto the adhesive to complete the testcomposite. In the case of adhesive systems II-3, the bonding acceleratoris coated onto both mating surfaces to provide a dry film thickness of0.3 mil. After the accelerator has dried, the polymerizable adhesivecomposition is coated onto one of the accelerator-coating matingsurfaces and the second accelerator-coated mating surface is pressedonto the adhesive mass to complete the test assembly. The total gluelineis approximately 12 mils for each test composite. The test pieces arecured at room temperature for 24 hours. Lap shear strength tests areperformed according to the procedure of ASTM D-1002-72. The results, inmegapascals (MPa), are reported in Table I.

                  TABLE I                                                         ______________________________________                                                  Lap Shear Strength, megapascals                                     Adhesive                                                                             Substrate                                                                              CRS.sup.a -                                                                            Al.sup.b -                                                                           Al-    Al-                                    System Prep'n.  1010     2024T3 5052-0 6061-T6                                ______________________________________                                        II-1   SW.sup.c  3.8      1.4    7.3   10.1                                   II-1   GB.sup.d 38.6     29.7   17.2   29.7                                   II-2   SW       37.5     22.2   12.1   35.2                                   II-3   SW       48.8     30.8   12.1   25.5                                   ______________________________________                                         .sup.a CRS is cold rolled steel of indicated type.                            .sup.b AL is aluminum of indicated type.                                      .sup.c SW is solventwiped.                                                    .sup.d GB is gritblasted and solventwiped.                               

The data demonstrate that the adhesive compositions of this inventionare effective to bond metal substrates without the need for extensivesurface preparation. For example, invention compositions 2 and 3 provideunexpectedly higher adhesion values in all instances in comparison tothe control adhesive 1 for the same degree of substrate preparation. Thecontrol adhesive, which does not utilize the concepts of the invention,requires the additional surface preparation step of grit-blasting inorder to approach the performance level obtained in the adhesives ofthis invention merely by solvent wiping of the mating surfaces. Acommercially available vinyl plastisol adhesive, Hughson HC-4177 vinylplastisol (Hughes Chemical Company, Detroit, Mich.), provides lap shearstrength adhesive values for aluminum bonding in the range 4.4-6.6megapascals depending on aluminum alloy being bonded and steel bondingin the range 5.5-7.2 megapascals. Commercial epoxy adhesive system suchas 3M Company, Minneapolis, Minn., EC-3443 and B. F. Goodrich ChemicalCompany, Cleveland, Ohio, A1340B systems report adhesion values foraluminum bonding in the range 9.9-18.6 megapascals, depending on alloy,and for steel bonding in the range 13.8-20.2 megapascals. The adhesivecompositions of this invention provide significantly enhanced adhesionfor both steel and aluminum vis-a-vis such vinyl plastisol and epoxyadhesive systems.

EXAMPLE III

Separate polymerizable adhesive compositions and bonding acceleratorcompositions are prepared having the formulations (amounts in parts byweight) as follows:

    ______________________________________                                        Adhesive System      III-1   III-2   III-3                                    ______________________________________                                        Polymerizable adhesive composition:                                           Chlorosulfonated polyethylene                                                                      30      30      30                                       Methyl methacrylate  10      10      10                                       2-methacryloyloxyethyl phosphate                                                                   --       1       2                                       Bonding accelerator:                                                          n-butyraldehyde-aniline condensation                                                               80      80      80                                       product                                                                       Monochlorotoluene    20      20      20                                       ______________________________________                                    

Following the primer mode of Example II, the adhesive systems areemployed to bond steel-steel and aluminum-aluminum composite assemblies.Lap shear strength test results are reported in Table II.

                  TABLE II                                                        ______________________________________                                        Adhesive                                                                              Substrate Lap Shear Strength, megapascals                             System  Prep'n.   CRS-1010     AL-6061-T6                                     ______________________________________                                        III-1   SW        25.2         27.3                                           III-2   SW        29.3         28.7                                           III-3   SW        33.1         27.3                                           ______________________________________                                    

The data clearly demonstrate the ability of the herein describedadhesive systems to provide significant adhesive values withoutextensive pretreatment of mating surfaces.

EXAMPLE IV

Adhesive systems are prepared according to the following formulations(amounts in weight percent):

    ______________________________________                                        Adhesive System         IV-1    IV-2                                          ______________________________________                                        Polymerizable adhesive composition:                                           Carboxylated poly(1,3-butadiene/                                                                      8.7     8.7                                           acrylonitrile) elastomer (Hycar                                               1072)                                                                         Poly(methyl methacrylate)                                                                             12.8    12.8                                          Methyl methacrylate     65.5    65.5                                          2-methacryloyloxyethyl phosphate                                                                      --      4.3                                           Diisopropanol-p-toluidine                                                                             1.3     1.3                                           N,N-dimethyl aniline    --      1.8                                           Molywhite (TM, Sherwin Williams) 212.sup.a                                                            --      4.4                                           Bonding accelerator:                                                          Benzoyl peroxide        8.0     8.0                                           Methylene chloride      66.0    66.0                                          Trichloroethane         14.4    14.4                                          Methyl isobutyl ketone  8.6     8.6                                           Syrup I                 3.0     3.0                                           ______________________________________                                         .sup.a Mixture of calcium molybdate (3 volumes) and zinc phosphate (2         volumes) on inert substrate.                                             

Following the primer method of Example II, the adhesive systems areemployed to bond steel-steel and aluminum-aluminum composite assemblies.Lap shear strength test results are reported in Table III.

                  TABLE III                                                       ______________________________________                                        Adhesive Substrate  Lap Shear Strength, megapascals                           System   Prep'n.    CRS-1010    AL-6061-T6                                    ______________________________________                                        IV-1     SW          2.6         6.6                                          IV-2     SW         22.8        27.4                                          ______________________________________                                    

The data demonstrate the ability of the herein-described adhesivesystems to provide significantly enhanced adhesion with minimalsubstrate preparation.

EXAMPLE V

Following the procedure of Example II, adhesive systems are preparedaccording to the following formulations (amounts in weight percent):

    ______________________________________                                        Adhesive                V-1     V-2                                           ______________________________________                                        Polymerizable adhesive composition:                                           Poly(vinyl methyl ether)                                                                              32.5    28.3                                          Carboxylated poly(1,3-butadiene/                                                                      7.5     6.4                                           acrylonitrile) elastomer, Hycar 1072                                          Methyl methacrylate     49.4    44.8                                          Methacrylic acid        9.0     7.8                                           2-methacryloyloxyethyl phosphate                                                                      --      4.3                                           Diisoproponil-p-toluidine                                                                             1.8     1.5                                           N,N-dimethylantline     --      1.6                                           Moly FR-21              --      4.4                                           Silica                  --      1.6                                           Bonding accelerator:                                                          Benzoyl peroxide        50      50                                            Dibutyl phthalate       50      50                                            ______________________________________                                    

After blending and agitating the ingredients of the polymerizableadhesive compositions and the bonding accelerator to obtain separatehomogeneous compositions, the adhesive systems are used for steel-steeland aluminum-aluminum metal bonding. The bonding accelerator is admixedwith the adhesive composition in an amount of 4 parts by weight per 100parts of adhesive composition. The fully-mixed adhesive system is coatedonto one mating surface and a second uncoated mating surface is pressedonto the adhesive to complete the test composite. The total gluelinethickness is approximately 10 mils for each test composite. The testpieces are cured at room temperature for 24 hours. Lap shear strengthtests are performed on the cured assemblies according to the procedureof ASTM D-1002-72. The test results, in megapascals, are reported inTable IV.

                  TABLE IV                                                        ______________________________________                                        Adhesive Substrate  Lap Shear Strength, megapascals                           System   Prep'n.    CRS-1010    AL-6061-T6                                    ______________________________________                                        V-1      GBB.sup.a  24.1        21.5                                          V-I      SW          3.8         5.6                                          V-II     SW         23.8        23.1                                          ______________________________________                                         .sup.a Glass bead blasted.                                               

The data further demonstrate the ability of the adhesive systems of thisinvention to provide significant adhesion values without the need forextensive pretreatment of mating surfaces.

EXAMPLE VI

Adhesive systems are prepared from the following ingredients (amounts inparts by weight):

    ______________________________________                                        Adhesive System II   1      2      3    4                                     ______________________________________                                        Polymerizable adhesive composition:                                           Polymer-in-monomer Syrup I (Ex. I)                                                                 93.2   93.2   40   40                                    Polymer-in-monomer Syrup II, Alt.  48   48                                    (Ex. I)                                                                       Unsaturated polyester resin (a resin                                          obtained from about equal parts                                               maleic-fumaric acid and 1,2-                                                  propylene glycol as a 60% solution                                            in styrene)          3.0    3.0    --   --                                    Polyester resin (a resin obtained                                             by the reaction of propylene                                                  glycol, phthalic acid and maleic                                              anhydride in a molar proportion                                               of 3.1:1.2 as a 75% solution in                                               methyl methacrylate) 1.0    1.0    --   --                                    Methyl methacrylate  2.0    4.0    1.3  3.3                                   Methacrylic acid     --     --     9.0  9.0                                   2-methacryloyloxyethyl phosphate                                                                   --     5.0    --   5.0                                   N,N-diisopropanol-p-toluidine                                                                      0.5    0.5    1.5  1.5                                   N,N-dimethylaniline  --     2.0    --   2.0                                   Paraffin wax         0.3    0.3    0.3  0.3                                   Silica               --     --     3.0  3.0                                   Bonding accelerator                                                           Benzoyl peroxide     50     50     50   50                                    Dibutyl phthalate    50     50     50   50                                    ______________________________________                                    

The bonding accelerator is admixed into the polymerizable adhesivecomposition in an amount of 4 percent by weight. The fully-admixedadhesive systems are employed for steel-steel and aluminum-aluminumbonding at room temperature. Bonding is effected by coating one matingsurface with the fully mixed adhesive system. An uncoated mating surfaceis pressed onto the adhesive mass to complete the test composite. Thecompleted composite is held under a slight pressure until polymerizationof the adhesive mass is completed. Lap shear strength test results, ASTMD-1002-72, in megapascals are reported in Table V.

                  TABLE V                                                         ______________________________________                                        Adhesive            Substrate Lap Shear Strength,                             System  Substrate   Prep'n.   megapascals                                     ______________________________________                                        VI-1    CRS-1010    SW        9.4                                             VI-2    CRS-1010    SW        28.8                                            VI-3    CRS-1010    SW        3.1                                             VI-4    CRS-1010    SW        18.8                                            VI-1    Al-6061-T6  SW        7.6                                             VI-2    Al-6061-T6  SW        27.8                                            VI-3    Al-6061-T6  SW        2.7                                             VI-4    Al-6061-T6  SW        13.2                                            ______________________________________                                    

The data demonstrate the unexpectedly strong adhesion values provided bythe adhesive compositions of this invention with minimal surfacepreparation.

EXAMPLE VII

The following adhesive systems are prepared (amounts in weight percent):

    ______________________________________                                        Adhesive System      VII-1   VII-2   VII-3                                    ______________________________________                                        Polymerizable adhesive composition:                                           Adhesive resin I (Ex. I)                                                                           17.68   17.1    16.9                                     Carboxylated Poly(1,3-butadiene/                                              acrylonitrile) elastomer                                                                           12.47   12.1    11.9                                     Methyl methacrylate  56.21   56.2    55.7                                     Methacrylic acid     8.90    8.6     8.5                                      2-methacryloyloxyethyl phosphate                                                                   --      5.0     5.0                                      N,N-diisopropanol-p-toluidine                                                                      1.3     1.2     1.2                                      N,N-dimethylaniline  --      --      1.0                                      Bonding accelerator                                                           Benzoyl peroxide     50      50      50                                       Dibutyl phthalate    50      50      50                                       ______________________________________                                    

After thorough mixing, the polymerizable adhesive compositions are eachdivided into several aliquot portions. The bonding accelerator isthoroughly mixed into one aliquot of each adhesive composition in anamount of 4 percent by weight of polymerizable adhesive composition. Theadmixtures are employed for bonding aluminum-aluminum at roomtemperature. To effect bonding, the fully-admixed adhesive system isapplied to one mating surface. The second mating surface is pressed ontothe adhesive mass and the completed composite is held under a slightpressure until sufficient strength for handling develops. Gluelinethickness is about 15 mils.

The remaining aliquots are stored at room temperature and 44° C. andemployed after storage of 1 week, 4 week and 8 weeks to bondaluminum-aluminum at room temperature, following the procedure set forthabove. Lap shear strength tests are performed, ASTM D-1002-72. Theresults are reported in the following Table:

    __________________________________________________________________________    Adhesive Stability Study                                                      Adhesive    Substrate                                                                           Storage                                                     System                                                                             Substrate                                                                            Prep'n.                                                                             Temp. t=0                                                                              1 Wk.                                                                             4 Wks.                                                                            8 Wks.                                     __________________________________________________________________________    VII-1                                                                              Al-6061-T6                                                                           GB    RT    29.3                                                                             20.3                                                                              24.4                                                                              28.2                                       VII-1                                                                              "      GB    44° C.                                                                       29.3                                                                             16.9                                                                              20.8                                                                              28.7                                       VII-2                                                                              "      SW    RT    11.4                                                                             15.8                                                                              21.8                                                                              18.2                                       VII-2                                                                              "      SW    44° C.                                                                       11.4                                                                             17.9                                                                              25.8                                                                              28.6                                       VII-3                                                                              "      SW    RT    32.7                                                                             29.6                                                                              33.7                                                                              33.7                                       VII-3                                                                              "      SW    44° C.                                                                       32.7                                                                             25.1                                                                              29.4                                                                              28.7                                       __________________________________________________________________________

The data demonstrate the excellent shelf-stability of the adhesivesystems of the invention, with very little decline in properties evenafter 8 weeks storage at the elevated temperature. The data alsodemonstrate the improvement in adhesive values realized by the additionof tertiary amines having the formula V, such as N,N-dimethylaniline, toadhesive systems containing the phosphorus compounds in accordance withthis invention.

EXAMPLE VIII

The following adhesive systems are prepared (amounts in weight percent):

    ______________________________________                                        Adhesive System  VIII-1  VIII-2  VIII-3                                                                              VIII-4                                 ______________________________________                                        Polymerizable adhesive                                                        composition:                                                                  Adhesive resin I (Ex. I)                                                                       17.1    17.7    17.7  --                                     Carboxylated Poly                                                                              12.1    12.5    12.5  --                                     (1,3-butadiene/                                                               acrylonitrile) elastomer                                                      Chlorosulfonated polyethylene                                                                  --      --      --    27.4                                   Methyl methacrylate                                                                            56.2    56.2    56.2  53.9                                   Methacrylic acid 8.6     8.9     8.9   9.1                                    Trimethylol propane                                                                            --      --      --    0.9                                    triacrylate                                                                   Bis-phenol A/epichlorohydrin                                                                   --      --      --    4.6                                    epoxy resin                                                                   2-methacryloyloxyethyl                                                                         5.0     --      --    --                                     phosphate                                                                     N,N-disopropanol-p-toluidine                                                                   1.2     1.3     1.3   --                                     Cumene hyaroperoxide                                                                           --      --      --    1.0                                    Silica           --      --      --    3.8                                    Bonding accelerator                                                           Benzoyl peroxide 50      8.0     50    --                                     n-butryaldehyde-aniline                                                                        --      --      --    80                                     condensation product                                                          Dibutyl phthalate                                                                              50      --      50    --                                     Methylene chloride                                                                             --      66.0    --    --                                     Trichloroethane  --      14.1    --    --                                     Methyl isobutyl ketone                                                                         --      8.6     --    --                                     Monochloro toluene                                                                             --      --      --    20                                     Syrup I (Ex. I)  --      3.0     --    --                                     2-methacryloyloxyethyl                                                                         --      1.5     --    --                                     phosphate                                                                     ______________________________________                                    

The adhesive systems are employed to bond steel-steel andaluminum-aluminum at room temperature. Bonding with adhesive systemsVIII-1 and VIII-3 is effected according to the procedure of Example VII,with the bonding accelerator mixed into the polymerizable adhesivecomposition prior to application of the fully-admixed adhesive system.With adhesive systems VIII-2 and VIII-4, the bonding accelerator is usedas a primer following the procedure of Example II. The test specimensare exposed for 500 hours to certain aggressive environments and testedfor lap shear strength, ASTM D-1002-72, following such exposure. Thetest results, in megapascals, are reported in the Table: 500 HourExposure of Lap Shear Speciments to Aggressive Environment. The data arefurther demonstrative of the significant adhesion values which areobtained by the adhesive systems of this invention without the necessityof extensive pretreatment of substrate surfaces.

EXAMPLE IX

The following adhesive systems are prepared (amounts in weight percent):

    ______________________________________                                        Adhesive System      IX-1   IX-2   IX-3 IX-4                                  ______________________________________                                        Polymerizable adhesive composition:                                           Adhesive resin I (Ex. I)                                                                           17.1   17.7   17.7 --                                    Carboxylated Poly(1,3-butadiene/                                                                   12.2   12.5   12.5 --                                    acrylonitrile) elastomer                                                      Chlorosulfonated polyethylene                                                                      --     --     --   27.4                                  Methyl methacrylate  56.2   56.2   56.2 53.9                                  Methacrylic acid     8.6    8.9    8.9  9.1                                   Trimethylolpropane triacrylate                                                                     --     --     --   0.9                                   Bis-phenol A/epichlorohydrin epoxy                                                                 --     --     --   4.6                                   resin                                                                         2-methacryloyloxyethyl phosphate                                                                   5.0    --     --   --                                    Diisopropanol-p-toluidine                                                                          1.2    1.3    1.3  --                                    N,N-dimethyl aniline 1.0    --     --   --                                    Cumene hydroperoxide --     --     --   1.0                                   Silica               --     --     --   3.8                                   Bonding accelerator                                                           Benzoyl peroxide     50     8.0    50   --                                    2-methacryloyloxyethyl phosphate                                                                   --     0.5    --   --                                    n-butyraldehyde-aniline con-                                                                       --     --     --   80                                    densation product                                                             Dibutyl phthalate    50     --     50   --                                    Methylene chloride   --     66.0   --   --                                    Trichloroethane      --     14.1   --   --                                    Methyl isobutyl ketone                                                                             --     8.6    --   --                                    Monochlorotoluene    --     --     --   20                                    Syrup I (Ex. I)      --     30     --   --                                    ______________________________________                                    

The adhesive are employed to bond steel-steel and aluminum-aluminum atroom temperature following the bonding procedure of Example VIII. Thetest specimens are exposed for 1000 hours to 5T salt spray at 38° C. andtested according to the test procedure of Example VIII. The testresults, in megapaschals, are reported in the Table: 1000 Hours Exposureof Lap Shear Specimens to 5% Salt Spray at 38° C.:

    ______________________________________                                        1000 Hours Exposure of Lap Shear Specimens                                    to 5% Salt Spray at 38° C.                                                               Lap Shear                                                   Adhesive          Strength, megapascals                                       System Substrate Substrate                                                                              Initial                                                                             Final % Retention                             ______________________________________                                        IX-1   CRS-1010  SW       37.5  29.0  78                                      IX-2   CRS-1010  SW       48.9  37.0  76                                      IX-3   CRS-1010  GB       38.7  33.0  87                                      IX-4   CRS-1010  SW       16.5  27.6  167                                     IX-1   Al-5052-0 SW       12.2  9.9   82                                      IX-2   Al-5052-0 SW       12.2  0.4   4                                       IX-3   Al-5052-0 GB       17.5  11.6  66                                      IX-4   Al-5052-0 SW       11.7  0.0   0                                       IX-1   Al-6061-T6                                                                              SW       31.7  20.4  65                                      IX-2   Al-6061-T6                                                                              SW       25.6  11.2  44                                      IX-3   Al-6061-T6                                                                              GB       29.1  22.0  76                                      IX-4   Al-6061-T6                                                                              SW       20.1  1.9   9                                       ______________________________________                                    

The data demonstrate that the addition of tertiary amines such asN,N-dimethylaniline can be effective to augment environmentalresistance.

EXAMPLE X

To aliquots of the polymerizable adhesive composition of adhesive systemXI-1 of Example IX there are added 5 percent by weight of polymerizableadhesive composition of the following corrosion inhibitor additives:dibasic lead phosphite, tribasic lead maleate, dibasic lead phthalate,Moly FR-21 (see Example II), and zinc oxide. The resulting adhesivesystems are employed to bond steel-steel and aluminum-aluminum at roomtemperature. Adhesive systems XI-1 and XI-3 of Example IX are used ascontrol systems. The bonding is effected according to the fully-mixedadhesive system motif of Example VIII. The test specimens are exposedfor up to 1000 hours to 100% relative humidity at 52° C. and testedaccording to the test procedure of Example VIII. The test results arereported in the Table: Comparison of Corrosion Inhibitors.

    __________________________________________________________________________    Comparison of Corrosion Inhibitors                                            Adhesive            Substrate                                                                          Lap Shear Strength, megapascals                      System                                                                             Inhibitor                                                                             Substrate                                                                            Prep'n.                                                                            t=o                                                                              500 hrs.                                                                           1000 hrs.                                                                          % Retention                             __________________________________________________________________________    IX-1 None    CRS-1010                                                                             SW   33.7                                                                             15.5 4.5  14                                                   Al-6061-T6                                                                           SW   31.2                                                                             7.5  0.7  2                                       IX-1 Dibasic lead                                                                          CRS-1010                                                                             SW   33.9                                                                             17.7 3.7  11                                           Phosphite                                                                             Al-6061-T6                                                                           SW   31.9                                                                             20.5 12.2 39                                      IX-1 Tribasic lead                                                                         CRS-1010                                                                             SW   32.4                                                                             17.0 2.0  6                                            Maleate Al-6061-T6                                                                           SW   31.3                                                                             20.0 9.1  29                                      IX-1 Dibasic lead                                                                          CRS-1010                                                                             SW   34.2                                                                             18.7 4.8  14                                           Phthalate                                                                             Al-6061-T6                                                                           SW   31.0                                                                             25.6 15.5 50                                      IX-1 Moly FR-21                                                                            CRS-1010                                                                             SW   38.3                                                                             20.8 6.0  16                                                   Al-6061-T6                                                                           SW   32.6                                                                             26.0 19.2 59                                      IX-1 Zinc oxide                                                                            CRS-1010                                                                             SW   31.8                                                                             19.9 9.3  30                                                   Al-6061-T6                                                                           SW   27.3                                                                             8.5  1.7  6                                       IX-3 None    CRS-1010                                                                             GB   37.5                                                                             27.1 14.5 39                                                   Al-6061-T6                                                                           GB   26.9                                                                             25.6 18.8 70                                      __________________________________________________________________________

The data demonstrate that lead salts of phosphorus acid and organicpolycarboxylic acids, zinc oxide and mixtures of molybdate salts withphosphate salts are effective to augment environmental resistance.

EXAMPLE XI

To aliquots of the polymerizable adhesive composition of adhesive systemVIII-3 containing no reducing agent, there are added varying amounts ofN,N-dimethyl aniline (DMA), a tertiary amine having the formula V, andN,N-diisopropanol-p-toluidine (DIIPT), a conventional and widely-usedamine reducing agent for redox couple catalyst system. The resultingadhesive systems are employed to bond aluminum-aluminum (Al-6061-T6) atroom temperature. Surface preparation of all mating surfaces is solventwiping only. Bonding is effected according to the procedure of ExampleX. Lap shear strength test results, ASTM D-1002-72, in megapascals arereported in the Table: N,N-Dimethylaniline/N,N-Diisopropanol-p-Toluidine Reducing Agents forPhosphate-Modified Polymerizable Adhesive Systems.

    ______________________________________                                        N,N-Dimethylaniline/N,N-Diisopropanol-p-Toluidine                             Reducing Agents for                                                           Phosphate-Modified Polymerizable Adhesive Systems                             Adhesive System X-1                                                           2 -3                                                                          3                                                                             4                                                                             5                                                                             ______________________________________                                        Polymerizable                                                                 adhesive composition                                                                       100     100     100   100   100                                  VIII-3                                                                        (no reducing agent),                                                          parts by weight                                                               Moles amine  .032    .032    .032  .032  .032                                 Fraction DMA 0       0.25    0.50  0.75  1.0                                  Fraction DIIPT                                                                             1.0     0.75    0.50  0.25  0.0                                  Handleable cure                                                                            30 hrs  3 hrs   80 min                                                                              50 min                                                                              25 min                               Lap shear                                                                     strength, MPa                                                                              21.4    28.7    29.2  32.6  32.5                                 ______________________________________                                    

The data demonstrate the significant reduction in cure time which isobtained by the addition of tertiary amines having the formula V.

EXAMPLE XII

The following adhesive systems are prepared (amounts in parts byweight):

    ______________________________________                                        Adhesive System XII                                                                          1      2      3    4    5    6                                 ______________________________________                                        Polymerizable                                                                 adhesive composition:                                                         Adhesive resin I (Ex. I)                                                                     17.1   17.1   17.1 17.1 17.1 17.1                              Carboxylated Poly                                                                            12.1   12.1   12.1 12.1 17.1 1.21                              (1,3-butadiene/                                                               acrylonitrile) elastomer                                                      Methyl methacrylate                                                                          56.2   56.2   56.2 56.2 56.2 56.2                              Methacrylic acid                                                                             8.6    8.6    8.6  8.6  8.6  8.6                               2-methacryloyloxyethyl                                                        phosphate      5.0    5.0    5.0  5.0  5.0  5.0                               N,N-diisopropanol-                                                            p-toluidine    1.2    --     1.2  1.2  1.2  1.2                               N,N-dimethylaniline                                                                          0      1.5    1.0  2.0  3.0  4.0                               Bonding accelerator                                                           Benzoyl peroxide                                                                             50     50     50   50   50   50                                Dibutyl phthalate                                                                            50     50     50   50   50   50                                ______________________________________                                    

The resulting adhesive systems are employed to bond steel-steel(CRS-1010) at room temperature. Bonding is effected according to theprocedure of Example VII. Lap shear tests (ASTM D-1002-72), gel time andexotherm time (time from initial mixing to peak temperature of reactionmass, that is, fully-admixed adhesive system). The results are reportedin the Table: Effect of N,N-dimethylaniline of Phosphate-ModifiedPolymerizable Adhesive Systems.

    ______________________________________                                        Effect of N,N-Dimethylaniline on                                              Phosphate-Modified Polymerizable Adhesive Systems                             Adhesive System XII                                                           2                                                                             3                                                                             4                                                                             5                                                                             6                                                                             ______________________________________                                        Gel Time, min >360    15     22.5 7.2  5    4.2                               Exotherm time, min.                                                                         --      27     49   12.0 9.8  7.8                               Lap shear strength, MPa                                                                     29.0    32.5   35.0 36.8 36.5 35.0                              ______________________________________                                    

The data further demonstrate the significant increase in speed of cureobtained through the addition of tertiary amines having the formula V topolymerizable adhesive compositions. The data demonstrate also theunexpected improvements in adhesion values which results from the use oftertiary amines having the formula V in combination with conventionalreducing components of redox couple catalyst systems.

    __________________________________________________________________________    500 Hour Exposure of Lap Shear Specimens to Aggressive Environment            Adhesive    Substrate              Salt    100% Relative                      System                                                                             Substrate                                                                            Prep'n.                                                                            Inital.sup.a                                                                      Gasoline-RT.sup.b                                                                     Water-RT.sup.c                                                                      Solution-RT                                                                           Humidity-52° C..sup.e       __________________________________________________________________________    VIII-1                                                                             CRS-1010                                                                             SW   38.2                                                                              38.9    43.5  42.0    11.0                               VIII-2                                                                             CRS-1010                                                                             SW   45.2                                                                              46.6    19.7  24.2    12.1                               VIII-3                                                                             CRS-1010                                                                             GB   38.5                                                                              40.4    39.5  39.7    28.4                               VIII-4                                                                             CRS-1010                                                                             SW   25.9                                                                              28.3    30.8  31.3    27.0                               VIII-1                                                                             Al-5182                                                                              SW   16.7                                                                              16.6    14.7  14.0    7.0                                VIII-2                                                                             Al-5182                                                                              SW   14.0                                                                              17.7    13.3  10.8    1.9                                VIII-4                                                                             Al-5182                                                                              SW   24.1                                                                              17.0    13.7  31.3    6.6                                VIII-1                                                                             Al-6061-T6                                                                           SW   27.5                                                                              26.7    25.0  23.3    5.5                                VIII-2                                                                             Al-6061-T6                                                                           SW   27.5                                                                              27.6    13.9  13.0    4.4                                VIII-3                                                                             Al-6061-T6                                                                           GB   26.7                                                                              30.3    26.1  28.9    25.9                               VIII-4                                                                             Al-6061-T6                                                                           SW   21.5                                                                              26.6    21.4  5.0     3.3                                __________________________________________________________________________     .sup.a After 24 hour room temperature cure.                                   .sup.b Immersion in regular gasoline at room temperature.                     .sup.c Immersion in tap water at room temperature.                            .sup.d Immersion in a 5% salt solution at room temperature.                   .sup.e 52° C. 100% relative humidity.                             

What is claimed is:
 1. A room temperature-curable adhesive systemcomprising1. as a polymerizable adhesive composition, a mixture of(1) apolymer-in-monomer syrup consisting essentially of(i) from about 2 toabout 60 percent by weight of at least one addition polymer; (ii) fromabout 10 to about 98 percent by weight of at least one polymerizableolefinically unsaturated compound having at least one >C═C< group; and(iii) from zero to about 30 percent by weight of a polymer containingthe group --CH₂ CCl═CH--CH₂)_(n), wherein n is an integer; wherein (i)and (ii) are present as a partial polymerization product of (ii) or of(ii) in the presence of (iii), the mixture of (i) and (ii) or of (i),(ii) and (iii) being a syrup of polymeric materials dissolved ordispersed in monomer, in which syrup the amount of (i) derived from (ii)is in the range from about 2 to about 90 percent by weight, based on thetotal weight of (i), (ii) and (iii); (2) from zero to about 5 percent byweight of polymerizable adhesive composition of at least one unsaturateddicarboxylic acid ester; (3) from zero to about 10 percent by weight ofpolymerizable adhesive composition of at least one usaturated polyesterresin;(4) from zero to about 20 percent by weight of polymerizableadhesive composition of at least one unsaturated carboxylic acid; (5)from zero to about 40 percent by weight of polymerizable adhesivecomposition of at least one monomeric acrylic or methacrylic acid ester,said ester (5) being in addition to any such ester employed in (1) (ii);(6) from zero to about 50 percent by weight of polymerizable adhesivecomposition of at least one polyvinyl alkyl ether; (7) from zero toabout 1 percent by weight of polymerizable adhesive composition of atleast one waxy substance selected from the group consisting of paraffinwax, montan wax, beeswax, ceresine wax and spermaceti wax; (8) aneffective amount of at least one phosphorus-containing compound havingthe formulae ##STR7## wherein each R is the same or different, and eachR is independently a divalent organic radical directly bonded to thephosphorus atom through a carbon-phosphorus bond, said divalent radicalbeing selected from the group consisting of divalent unsubstitutedorganic radical and divalent organic radical having at least onesubstitutent group selected from the class consisting of halogen,hydroxyl amino, alkyl radical containing from 1 to 8 carbon atoms andaryl radical having at least one moiety containing at least one aromaticnucleus; and wherein each X is the same or different, and each X isindependently a functional group selected from the class concisting ofhydrogen, hydroxyl, amino, mercapto, halogen and CH₂ ═C≧; ##STR8##wherein R and X are as previously defined; and R¹ is hydrogen or --R²--X, wherein R² is a divalent organic radical directly bonded to theoxygen radical through a carbon-oxygen bond, said divalent radical R²being selected from the group consisting of divalent unsubstitutedorganic radical and divalent organic radical having at least onesubstituent group selected from the class consisting of halogen,hydroxyl, amino, alkyl radical containing from 1 to 8 carbon atoms andaryl radical having at least one moiety containing at least one aromaticnucleus and X is as previously defined; and ##STR9## wherein R¹ is aspreviously described; (9) an effective amount of at least one reducingagent; (10) from 0.01 to about 10 percent by weight of polymerizableadhesive composition of at least one tertiary amine having the formula##STR10## wherein Z is methylene; Y is selected from the groupconsisting of hydrogen, hydroxy, amino, halogen, alkyl radical havingfrom one to 8 carbon atoms, and alkoxy radicals wherein the alkyl moietyhas from one to 8 carbon atoms; and a is zero or 1; and b is one or two;(11) from zero to about 15 percent by weight of polymerizable adhesivecomposition of a mixture of a metal molybdate selected from the groupconsisting of zinc molybdate, calcium molybdate, barium molybdate,strontium molybdate and mixtures thereof and a metal phosphate selectedfrom the group consisting of zinc phosphate, calcium phosphate,magnesium phosphate and mixtures thereof; said metal molybdate beingpresent on a volume concentration basis of from about 2 to about 3 partsper part of said metal phosphate; and (12) from zero to about 15 percentby weight of polymerizable adhesive composition of at least one compoundselected from the group consisting of polybasic lead salts of phosphorusacid, polybasic lead salts of unsaturated organic dicarboxylic acids andacid anhydrides, polybasic lead salts of unsaturated organicdicarboxylic acids and acid anhydrides, zinc oxide, and mixturesthereof;the amount (1), in weight percent, being 100 minus the combinedweight percent of (2) through (12); and II. as a bonding accelerator, aneffective amount of at least one oxidizing agent, said oxidizing agentbeing reactive at room temperature with said reducing agent to generatefree radicals effective to initiate addition polymerization of saidpolymerizable adhesive composition.
 2. An adhesive system according toclaim 1 wherein said bonding accelerator contains from about 0.05 toabout 50 percent by weight of at least one organic polymericfilm-forming binder material selected from the group consisting ofsaturated organic 1 olymeric composition having a glass transitiontemperature in the range from about 0° C. to about 150° C. andpolymer-in-monomer syrup, said polymer-in-monomer syrup consistingessentially of(i) from about 2 to about 60 percent by weight of at leastone addition polymer; (ii) from about 10 to about 98 percent by weightof at least one polymerizable olefinically unsaturated compound havingat least one >C═C≧ group; and (iii) from zero to about 30 percent byweight of a polymer containing the group --CH₂ CCl═CH--CH₂)_(n), whereinn is an integer;wherein (i) and (ii) are present as a partialpolymerization product of (ii) or of (ii) in the presence of (iii), themixture of (i) and (ii) or of (i), (ii) and (iii) being a syrup ofpolymeric materials dissolved or dispersed in monomer, in which syrupthe amount of (i) derived from (ii) is in the range from about 2 toabout 90 percent by weight, based on the total weight of (i), (ii) and(iii); and from about 40 to about 99 percent by weight of a carriercomprising at least one inert organic diluent, said carrier vehiclebeing capable of maintaining said oxidizing agent and said film-formingbinder material as a stable solution or dispersion.
 3. An adhesivesystem according to claim 1 comprising(I) as a polymerizable adhesivecomposition, a mixture of(1) a first syrup of polymethylmethacrylate,polystyrene and polychloroprene in monomeric methyl methacrylate andstyrene, said first syrup being in the form of a partial polymerizationproduct of methyl methacrylate and styrene in polychloroprene, thepolychloroprene being present in an amount from about 1 to about 25percent by weight of polychloroprene, methyl methacrylate and styrene,the balance being essentially methyl methacrylate and styrene with themethyl methacrylate predominating; (2) methacrylic acid; (3) a secondsyrup of at least one polymer of at least one alkyl ester of acrylic ormethacrylic acid, the alkyl moiety of such ester having from one to 8carbon atoms, said second syrup being in the form of a partialpolymerization product of said alkyl ester in methyl methacrylate, saidpolymer being present in an amount in the range from about 15 to about60 percent by weight of said second syrup;the relative proportions of(1), (2) and (3) being from about 10 to about 52 percent by weight of(1), from about 7 to not more than 15 percent by weight of (2) and fromabout 33 to about 83 percent by weight of (3); (4) an effective amountof at least one phosphorus-containing compound having the formulae##STR11## wherein each R is the same or different, and each R isindependently a divalent organic radical directly bonded to thephosphorus atom through a carbon-phosphorus bond, said divalent radicalbeing selected from the group consisting of divalent unsubstitutedorganic radical and divalent organic radical having at least onesubstituent group selected from the class consisting of halogen,hydroxyl, amino, alkyl radical containing from 1 to 8 carbon atoms andaryl radical having at least one moiety containing at least one aromaticnucleus; and wherein each X is the same or different, and each X isindependently a functional group selected from the class consisting ofhydrogen, hydroxyl, amino, mercapto, halogen and CH₂ ═C>; ##STR12##wherein R and X are as previously defined; and R¹ is hydrogen or --R²--X, wherein R² is a divalent organic radical directly bonded to theoxygen radical through a carbon-oxygen bond, said divalent radical R²being selected from the group consisting of divalent unsubstitutedorganic radical and divalent organic radical having at least onesubstituent group selected from the class consisting of halogen,hydroxyl, amino, alkyl radical containing from 1 to 8 carbon atoms andaryl radical having at least one moiety containing at least one aromaticnucleus and X is as previously defined; and ##STR13## wherein R¹ is aspreviously described; (5) an effective amount of at least one reducingagent; (6) from 0.01 to about 10 percent by weight of polymerizableadhesive composition of at least one tertiary amine having the formula##STR14## wherein Z is methylene; Y is selected from the groupconsisting of hydrogen, hydroxy, amino, halogen, alkyl radical havingfrom one to 8 carbon atoms, and alkoxy radicals wherein the alkyl moietyhas from one to 8 carbon atoms; a is zero or one; and b is one or two;(7) from zero to about 15 percent by weight of polymerizable adhesivecomposition of a mixture of a metal molybdate selected from the groupconsisting of zinc molybdate, calcium molybdate, barium molybdate,strontium molybdate and mixtures thereof and a metal phosphate selectedfrom the group consisting of zinc phosphate, calcium phosphate,magnesium phosphate and mixtures thereof; said metal molybdate beingpresent on a volume concentration basis of from about 2 to about 3 partsper part of said metal phosphate; and (8) from zero to about 15 percentby weight of polymerizable adhesive composition of at least one compoundselected from the group consisting of polybasic lead salts of phosphorusacid, polybasic lead salts of unsaturated organic dicarboxylic acids andacid anhydrides, polybasic lead salts of unsaturated organicdicarboxylic acids and acid anhydrides, zinc oxide, and mixturesthereof; and II. as a bonding accelerator, an effective amount of atleast one oxidizing agent, said oxidizing agent being reactive at roomtemperature with said reducing agent to generate free radicals togenerate free radicals effective to initiate addition polymerization ofsaid polymerizable adhesive composition.
 4. An adhesive system accordingto claim 3 wherein said bonding accelerator contains from about 0.05 toabout 50 percent by weight of at least one organic polymericfilm-forming binder material selected from the group consisting ofsaturated organic polymeric composition having a glass transitiontemperature in the range from about 0° C. to about 150° C. andpolymer-in-monomer syrup, said polymer-in-monomer syrup consistingessentially of(i) from about 2 to about 60 percent by weight of at leastone addition polymer; (ii) from about 10 to about 98 percent by weightof at least one polymerizable olefinically unsaturated compound havingat least one >C═C≧ group; and (iii) from zero to about 30 percent byweight of a polymer containing the group --CH₂ CCl═CH--CH₂)_(n), whereinn is an integer; wherein (i) and (ii) are present as a partialpolymerization product of (ii) or of (ii) in the presence of (iii), themixture of (i) and (ii) or of (i), (ii) and (iii) being a syrup ofpolymeric materials dissolved or dispersed in monomer, in which syrupthe amount of (i) derived from (ii) is in the range from about 2 toabout 90 percent by weight, based on the total weight of (i), (ii) and(iii); and from about 40 to about 99 percent by weight of a carriervehicle comprising at least one inert organic diluent, said carriervehicle being capable of maintaining said oxidizing agent and saidfilm-forming binder material as a stable solution or dispersion.